Battery Sub-Pack Venting Structure for Flame Propagation Control
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Solution Overview
Problem
Secondary battery cells generate heat during charging and discharging, leading to increased temperature and pressure, which can result in ignition and potential explosion, with flames propagating between adjacent cells, posing a risk of chain reactions and harm to occupants in vehicles or systems.
Innovation Solution
A battery sub-packing unit with a case that includes a sub-vent hole and a surrounding cover to discharge high-temperature and high-pressure flames and gases externally, using a metal material with a melting point above 1000°C and an insulating central portion, and an inner pad generating carbon dioxide or nitrogen to block oxygen inflow and extinguish flames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If battery cells are densely mounted to increase energy density, then productivity and energy storage capacity improve, but the risk of flame propagation and thermal runaway between adjacent cells increases
Solution Approach 1:
The case is divided into multiple independent compartments, each accommodating a single battery cell. These compartments are separated by partition walls that physically isolate adjacent cells, preventing flame and thermal runaway propagation while maintaining high energy density through efficient space utilization.
Solution Approach 2:
Fire-resistant partition walls and thermal insulation layers are introduced as intermediary structures between adjacent battery cells. These intermediaries act as barriers that block heat transfer and flame propagation, allowing cells to be mounted closely together without increasing safety risks.
2Reliability
If vent holes are added to the case to discharge flames and gases, then safety against thermal runaway improves, but the structural integrity and sealing of the case deteriorates
Solution Approach 1:
The case structure is designed with different properties in different locations: the majority of the case maintains high strength and sealing properties, while localized vent holes with flame-arresting meshes are introduced at specific positions. This allows flame discharge functionality to be added without compromising the overall structural integrity, as the vent holes are small, strategically placed, and reinforced with fire-resistant materials.
3Temperature
If metal materials with high melting points are used for the case, then resistance to high-temperature flames improves, but the weight and manufacturing complexity of the case increases
Solution Approach 1:
The case is constructed using composite materials that combine the advantages of different materials: a metal framework or reinforcement structure provides high-temperature resistance and structural strength, while plastic or polymer components reduce overall weight and provide ease of manufacturing. This composite approach achieves flame resistance without the full weight penalty of solid metal construction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents flame propagation between battery cells, minimizing risk to occupants by discharging flames externally and extinguishing them quickly, thus enhancing safety in vehicles and systems.
Implementation Method 1
a lower end portion in which a sub-vent hole is formed for communication between the external space and an internal space in which the at least one battery cell is disposed
Implementation Method 2
an inner pad generating carbon dioxide or nitrogen to block oxygen inflow and extinguish flames
Data Source
AI summary
A battery sub-packing unit includes at least one battery cell; and a case accommodating the at least one battery cell, wherein the case comprises an end panel on which an electrode tab of the at least one battery cell is fastened to extend into an external space, and having a lower end portion in which a sub-vent hole is formed for communication between the external space and an internal space in which the at least one battery cell is disposed.